P0202 OBD2 Code Guide
P0202 is a powertrain diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
Injector Circuit Malfunction - Cylinder 2
Code P0202 signifies that the Powertrain Control Module (PCM) has detected an electrical malfunction within the fuel injector circuit specifically for cylinder #2. This means the PCM is not observing the expected voltage drop or resistance characteristics when it attempts to activate the injector. It could indicate an open circuit (no continuity), a short to ground, a short to voltage, or an internal fault within the injector's coil winding, preventing proper fuel delivery to the cylinder. This typically results in a misfire condition for cylinder #2.
Code verification standard
P0202 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 P0202 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
P0202 diagnostic path
- 11. Perform a thorough visual inspection of the wiring harness and connector for the cylinder #2 fuel injector. Look for any signs of damage, fraying, corrosion, or loose connections. Ensure the connector is fully seated and locked.
- 22. Disconnect the fuel injector for cylinder #2 and measure its internal resistance using a digital multimeter. Compare this reading to manufacturer specifications (typically 10-18 ohms for most vehicles). An 'OL' (open circuit) reading or a resistance significantly outside the specified range indicates a faulty injector.
- 33. With the ignition ON and engine OFF, check for battery voltage at one terminal of the injector connector (the power supply side, which is usually shared with other injectors). Then, with the injector still disconnected, check for continuity between the PCM driver wire (signal side) and ground, and between the driver wire and battery voltage. This helps identify any shorts or open circuits in the wiring.
- 44. Using a noid light or an oscilloscope, connect it to the injector connector for cylinder #2. Crank the engine (or allow it to run if possible). The noid light should flash, or the oscilloscope should display a clear pulse pattern. If no pulse is observed, the PCM's injector driver circuit or the wiring leading to the PCM is suspect. If a pulse is present but the injector resistance was good, the injector might be mechanically stuck or clogged.
Verify before repair
- - Repair or Replace Damaged Wiring or Connector: If visual inspection or continuity tests reveal damaged wires, chafing, or corroded/loose terminals in the injector circuit for cylinder #2, repair or replace the affected section of the wiring harness or the connector.
- - Replace Fuel Injector for Cylinder #2: If the injector's internal resistance is out of specification (open circuit or shorted) or if it fails the noid light/oscilloscope test despite a good PCM driver signal, the injector itself is faulty and needs replacement.
- - Repair or Replace Powertrain Control Module (PCM): If all wiring, connectors, and the injector itself test good, and there is no driver signal from the PCM, the PCM's injector driver circuit for cylinder #2 may be faulty. This is less common but requires professional diagnosis and potentially reprogramming.
Vehicle-specific pages to check next
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